204: PRINCIPLES OF BOTANY, ETC. 
ness in employing them, he will yet find difficulty 
in determining plants he has never seen before. In 
this case the following directions are to be ob- 
served > | | 
In the first place he is accurately to examine the 
flower, and endeavour to refer it to its class and 
order, by attending to the number, proportion, and 
connexion of the parts of the fructification. When he 
has succeeded in this, he seeks out the genus in his 
system. Here, however, he may encounter some difh- 
culties, which he must carefully endeavour to over- 
come. 
The stamina, and likewise the pistillum, often vary 
according to the soil and climate in which the plant 
has grown, so that sometimes there is a stamen more 
or less than there should be: in this case he must 
examine many flowers, and be ruled by the ma- 
jority. There is often likewise a luxuriance in 
plants, which doubles the number of parts; and often 
a defect, when a half is wanting: thus sometimes 
there are eight instead of four stamina, and some- 
times only two. When in this case he cannot find 
the plant in the class where he thinks it ought to be, 
he must try the other classes where it may be. Some- 
‘times the anthereze and filaments are united, which is 
not the case in other species, and the sex also. is 
subject to variation. ‘Therefore, when a plant is not 
found in the class to which it seems to belong, he 
must search the 21st, 22d and 23d classes. If he 
is convinced after these searches that the plant is 
new, he must describe it as such. Dr Roth and 
Professor Hedwig have done an essential service to 
botany 
